LONG-TERM EFFECTS OF STROKES ON BONE MASS

The purpose of the study was to determine the long-term effects of mus cle weakness secondary to strokes on the bone mineral content of the h emiparetic limb. Patients who had experienced single recent strokes we re studied. The bone mineral content of each limb was measured by Dual Energy X-ray Absorptiometry using the region of interest analysis pro gram. Muscle strength of each muscle group was ranked using the Oxford scale, and the mean was calculated for each limb. Bone and muscle par ameters were measured within seven days after the stroke and repeated thereafter at monthly intervals for up to 6 mo. A repeated measures an alysis of variance, Newman-Keuls pair-wise comparisons, and orthogonal contrasts were done for each parameter. Significance levels were set at P < 0.05. Sixteen patients were included in this study. Demineraliz ation was more pronounced in the upper than lower limbs. Demineralizat ion of bones on the paralyzed side started during the first month afte r the stroke and gradually progressed. By the fourth month, the bone m ineral content decreased by a mean of 9.3% (P = 0.01) and 3.7% (P = 0. 01) in the upper and lower limbs, respectively, for the 11 patients fo llowed for 4 mo. In the patients we followed for more than 4 mo, there was no further significant mineral loss. No change in bone mineral co ntent was observed in the healthy nonparetic limbs. In conclusion, aft er a stroke, bone demineralization occurs in the paralyzed side and re aches its maximum within 3 to 4 mo. Arms are affected more than legs.